It is often useful to detect the position of a knob, lever, or other mechanism. For example, the vast majority of vehicles today employ automatic transmissions. A driver may use a lever or the like to direct the automatic transmission to change gears. Sensors may be used to detect a position of the lever, and hence detect the driver's intent with respect to the status of the vehicle's transmission, i.e., how the driver intends the vehicle engine to be presently geared.
For example, a driver of a passenger car may generally select park, reverse, neutral, drive, and low as positions of a selection mechanism for an automatic transmission. A driver of a medium duty or heavy-duty truck may select park, reverse, neutral, drive, hold, and low as positions of a selection mechanism for an automatic transmission. In either case, the selection mechanism is generally biased so that the knob, lever, etc., used in the selection mechanism naturally settles in a detent position, e.g., park, reverse, etc., when moved. However, when a driver is in the act of moving the knob, lever, etc., the selection mechanism may be in a transition position between two detent positions.
By analyzing sensor inputs to determine a position of a selection mechanism, a processor can provide appropriate instructions for a device to act according to the position of the selection mechanism. For example, when a driver moves an automatic transmission selector from “park” to “reverse,” a transmission control module (TCM) may detect a new position of the automatic transmission selector, e.g., reverse, and may accordingly instruct an automatic transmission to transition a vehicle from a “park” state to a “reverse” state.
Unfortunately, present mechanisms for determining a position of a selection mechanism are generally lacking with respect to detection of errors and failure states. Further, present mechanisms for determining a position of a selection mechanism lack robustness. For example, although it is critical to safe operation of a vehicle to be able to detect a driver's intent with respect to the state of an automatic transmission, present arrangements of sensors do not necessarily provide assurance that the driver's intent will be properly detected. And even when errors and failures states are detected, present mechanisms lack ways of determining whether such error or failure state is critical, e.g., whether upon an error or failure state vehicle operation must cease, or may be allowed to continue for a period of time. Further, it is at present generally difficult, if not impossible, to operate a vehicle once error conditions have been detected in a vehicle, e.g., in an automatic transmission selector detection mechanism.